Imperforate deck panel with flush tie-down fittings



June 12, 1962 H. F. BRINKER ET AL 3, 3

IMPERFORATE DECK PANEL WITH FLUSH TIE-DOWN FITTINGS Filed Feb. 28, 1956 2 Sheets-Sheet 1 INVENTORSI HARRY l BR/I'V/(ER 0/70 JOl-l/V CLARK,

their Af/orney.

June 12, 1962 H. F. BRINKER ETAL 3,038,394

IMFERFORATE DECK PANEL WITH FLUSH TIE-DOWN FITTINGS Filed Feb. 28, 1956 2 Sheets-Sheet 2 wvEA/mRs: HARRY F RRl/VRER and JOHN CLARK,

fhe/r Attorney United States Patent Ofifice 3,038,394 Patented June 12, 1962 3,038,394 IMPERFORATE DECK PANEL WITH FLUSH TIE-DGWN FITTINGS Harry F. Brinker, Whitaker, and John Clark, Munhall, Pa., assignors to United States Steel Corporation, a corporation of New Jersey Filed Feb. 28, 1956, Ser. No. 568,368 1 Claim. (CI. 94-11) This invention relates to a panel adapted to be laid in the hull of an aircraft carrier to constitute the flight and hanger decks thereof.

It is essential to provide the flight and hangar decks of aircraft carriers with tie-down fittings for securely anchoring airplanes maneuvering thereon. The fittings must be recessed or flush in order to leave the deck flat and unobstructed. The deck panels are quite thick (up to 2") and are composed of specially treated alloy steel, in order to afford the high strength desired for sustaining airplane-wheel loads and resistance to battle damage by explosive blast or projectiles. The provision of the necessary recesses for flush tie-down fittings thus poses a difficult problem.

One method which has been used is to cut holes in the panels, forming the wall of each hole as the frustum of an inverted cone, and weld therein a cup-shaped forged plug having cross bars extending across the top thereof. This method is laborious, costly and time-consuming. A more serious objection is the weakening of the panels resulting from the cutting of the holes, and the low resistance of the welded-in plugs to being blown through the holes by blasts occurring above the deck.

We have invented a novel deck panel which fully overcomes the aforesaid objections and a method by which it may be readily manufactured, based on the discovery of a practice whereby the plates used for making the panels, despite their considerable thickness and great hardness and tensile strength, may be die-drawn cold to provide the necessary recesses. Our panel is entirely free from holes, the original metal thereof remaining unbroken at all points when manufacture is completed. The panel comprises a plate having die-formed depressions spaced therealong, each depression comprising a bottom which has the shape of a spherical segment and a rim in the form of a portion of an annulus. More specifically, the depression has the smoothly curved shape of a surface of revolution obtained by revolving about a vertical axis a segment of a circle concave upwardly and symmetrical relative to the axis, with a minor reverse curve at each end thereof. A cruciform forging or cross bar is laid in each depression and Welded to the plate flush with the upper surface thereof.

In making our panel, we roll steel of suitable composition to a plate of the desired thickness, shear it to size, heat-treat it by quenching and tempering, flatten it cold and then subject it to cold die-drawing to form the depressions, after which the panel is ready for laying in the hull. The cruciform forgings or cross bars may be welded in place either before or after the panel is laid. The dies are shaped to form a smoothly curved reverse bend or hump in the plate around the rim of the depression as the latter is drawn. This temporary overdeformation is controlled to compensate precisely for the spring-back which occurs as the die pressure is released, leaving the plate in its original condition of flatness, except for the areas of the depressions. Our method is also disclosed and claimed in our Patent 2,904,881, a division hereof.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment and practice. In the drawings:

FIGURE 1 is a plan view of a panel according to our invention, with the mid-portion broken out;

FIGURE 2 is an edge view thereof partly broken away and greatly reduced in scale;

FIGURE 3 is a plan view of one of the depressions in the panel and the area immediately surrounding it;

FIGURE 4 is a partial section taken along the plane of line IVIV of FIGURE 3;

FIGURE 5 is an elevation partly broken away, showing the cooperating punch and die for forming the depressions in the plate;

FIGURE 6 is a side elevation showing the stationary platen or base and the movable crosshead of a die forming press having the die and punch of FIGURE 5 mounted therein, respectively; and

FIGURE 7 is an end elevation thereof.

Referring now in detail to the drawings and, for the present, particularly to FIGURES 1 through 4, our improved panel comprises a plate 10 of a length L, width W and thickness T, appropriate for use in the flight deck or hangar deck of an aircraft carrier, composed of a suitable alloy steel, has spaced depressions 11 formed therein in spaced rows parallel to the side edges thereof. A cruciform anchorage fitting or cross bar 12 overlies each depression and has its ends welded to the plate inwardly of the rim of the depression. Plate 114 may, for example, be l2x35 and up to 2" thick, rolled from nickel-chromium or nickel-chromium-molybdenurn steel. The depressions 11 may conveniently be about 10" in diameter and about ?1.5 deep at the center.

The depressions are bowl shaped, i.e., they are defined by a smooth gradual curve in all directions and are free from sharp bends and corners. Each depression includes a bottom portion 1 1a which is a segment of a sphere, concave upwardly, and a rim zone 11b, convex upwardly, which is a portion of the surface of an annulus, the continuation of which is indicated in broken lines at 13 in FIGURE 4. The radius 'R of the sphere of which portion 11a is a segment should be about 3.5 times the thickness T. The radius R of the section of the annulus of which Zone 11b is a part should be about 2.5 times the thickness T. These ratios give a depression having a depth approximating T. The diameter of the depression in the plane of the plate is about 5T.

It will be evident that the interior and exterior of the depression are surfaces of revolution formed by rotating curves AA and A--A', respectively, about axis XX. Each of these curves includes a principal central circular are symmetrical relative to the axis, with a minor reverse curve at each end. This conformation results in smooth, easy and uniform flow of metal in the stretching caused by the shaping dies, with minimum stress and tendency toward cracking or tearing. The deformation effected by die-drawing causes a reduction in the thickness of the metal between the center and rim of the depression, e.g., from 1.75 to 1.5".

Cross bar 12 has radial arms round in section which are beveled at the ends on the lower side as at 14, to fit snugly in the depression and on their upper sides as at 15 to form a V-notch with the interior of the depression, to receive a deposit of weld metal 12a. When the cross bars are thus installed, ample clearance is afforded between them and the bottoms of the depressions to admit the terminal hooks of securing lines.

The apparatus and method by which we are enabled to produce the panels described above will now be explained with reference more particularly to FIGURES 5 through 7. A heat of the desired alloy steel is made and teemed into ingots. Each ingot, after being cropped, is reduced to a plate of the required thickness by rolling in conventional blooming, slabbing and plate mills. The rolled plates are sheared to size and given a heat-treatment by quenching from a temperature above the critical point and tempering to develop their maximum hardness and tensile strength consistent with the minimum ductility required for toughness. The exact details of such treatment will vary depending on the composition of the steel used, but such details are known to skilled rnetallurgists and therefore require no elaboration. After heat-treatment, the plates have a Brinell hardness of about 235 and a tensile strength of about 112,000 psi. They are then flattened in a leveler or forging press. The heattreated, flattened plates are then subjected to repeated cold die-drawing to form the depressions 11 individually at the desired locations. At all times after heat-treatment, the plates must be kept below 500 F. to prevent disturbing their quenched and tempered condition, except at the welds where only small areas are involved.

The depressions are formed by the successive application to the plates of the forging dies shown in FIGURE 5, of which the male or punch 16 is mounted on the slide or crosshead 17 of a conventional forging press 18 of high capacity, and the female die or matrix 19 rests on the base or platen 20 thereof. The punch fits in a trough in the slide and is adjustable therealong by virtue of being carried by through bolts 21 extending through slots in the slide and the upper portion of the punch. The matrix fits in a trough in base 20 and is slidable therein by means of ropes 22 attach-able thereto, one at a time, and to one end of the slide. The ropes are trained around sheaves 23 so that a pull in one direction or the other will be exerted on the matrix when one rope is attached thereto, by raising the slide. Posts 24 upstanding on base 20 guide movement of the crosshead toward and from the base. Screw shaft-s 25 threaded through the posts at one end of the press carry push blocks 26 for accurately positioning a plate suspended between the punch and matrix as shown in FIGURES 6 and 7, by suitable traveling cranes on opposite sides of the press. When the plate has been properly spot-ted, closure of the punch on the matrix draws the metal of the plate and forms a depression 11.

Punch 16 has a nose 16a which is a segment of a sphere, and a frusto-conical shoulder 16b. The nose and shoulder are connected by a smoothly curved surface which is a portion of an annulus. The radius of the sphere and the radius of the section of the annulus should be about 3T. Matrix 19 has a central cavity 19a which is a segment of a sphere, and a frusto-conical shoulder 19b connected thereto by an annular surface. The radius of cavity 19a should be about 3.5T and the radius of the section of the connecting annulus in the neighborhood of T.

When the punch is brought down on the plate, after applying a suitable lubricant in the area to be deformed, the frusto-conical shoulders 16b and 19b impart a temporary reverse curvature to the plate in the area thereof bordering the depression, as the metal is deformed by die-drawing. In other words, a slight excess deformation is effected to compensate for the natural spring-back of the metal as the punch is withdrawn. This leaves the plate flat within a small tolerance, in the area surrounding the depression, instead of slightly dished as it would be otherwise.

The cross bars are secured in place by arc-welding in the known manner. Our invention is characterized by numerous advantages. In the first place, it provides an imperforate deck panel free from holes which are a P0 tential source of weakness under blast, even though closed by Welded-in plugs. Despite the thickness and great strength of the plate, the integral depressions can be safely formed by proper dies and a forging press of the required capacity. The mild cold-working of the plate by the dies in the regions of the depressions does not impair the physical properties of the metal. Cold die-drawing performed as described, after heat-treatment and flattening, with compensation for spring-back, furthermore, avoids distributing the flat condition originally imparted to the plate except, of course, for the depressions themselves. The smooth curvature of the dies at all points minimizes any tendency to tear or crack the metal during drawing.

The cross bars are wholly below the plate surface, can easily be fixed in place with a minimum of welding, and are well adapted to withstand heavy shock loads such as are imposed by the wheel of an airplane in landing. They are also suited for mass production. Damage to the cross bars by blast will not result in projections above the deck level to foul arrestor lines or hooks.

Although we have disclosed herein the preferred embodiment of our invention, we intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.

We claim:

As an article of manufacture, an integral imperforate airplane-carrier deck panel comprising a steel armor plate of a thickness of about /2", said plate being generally fiat and having a strength sufficient to sustain the wheel loads imposed by airplanes landing thereon, the metal of said plate being downwardly displaced at points located in spaced relation along the length thereof to form bowl-shaped depressions, each depression having a depth approaching the thickness of the'plate, a diameter of the order of 5 times said thickness, both the upper and lower surfaces of said plate at the periphery of said depressions being surfaces of revolution generated by substantially equally spaced lines composed entirely of smooth curves, the bottom of each depression being a spherical segment having an inside radius about 3.5'times said thickness, said periphery of each depression on both upper and lower surfaces of the plate being a portion of the surface of an annulus which portion merges smoothly into said segment on one side and into the flat body of the plate on the other, thereby preventing substantial impairment of ductility and toughness of said portion as a result of cold-forming, the radius of the section of the annulus defining said rim on the upper side of the plate being about 2.5 times said thickness, and an anchorage bar welded in each depression.

References Cited in the file of this patent UNITED STATES PATENTS 520,654 Moxham May 29, 1894 1,168,982 Walker Jan. 18, 1916 1,834,444 Bock Dec. 1, 1931 1,923,657 Beers Aug. 22, 1933 1,937,769 Lute Dec. 5, 1933 1,973,624 Hanlon Sept. 11, 1934 2,230,506 Vissering Feb. 4, 1941 2,375,454 Wichert May 8, 1945 2,642,965 Danhier June 23, 1953 2,733,671 Sheesley Feb. 7, 1956,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,038,394 June 12 1962 Harry F, Brinker et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 11 for "distributing" read disturbing line 30, for read 1%" Signed and sealed this 9th day of October 1962.

v (SEAL) ERNEST W. SWIDER Commissioner of Patents Attesting Officer 

